A nice article in the Washington Post today about a food co-op run by Amish farmers who supply produce to more than 50 Washington D.C. restaurants.
This is a classic social dilemma - it is any one farmer's interest to grow more and potentially break out on their own, but if all do this the restaurants will likely get frustrated and stop purchasing.
Per Elinor Ostrom's work on Common Pool Resources, these farmers "...set up a board to delegate growing responsibilities and establish bylaws." That is, they self-imposed rules and sanctions such as who gets to grow which produce and when. All the farmers signed on, and the co-op is incredibly successful.